The present invention relates to an eyeglass lens processing apparatus that processes a periphery of an eyeglass lens.
In general, an eyeglass lens processing apparatus has a lens chuck shaft which holds an eyeglass lens, a processing tool rotational shaft to which processing tools (roughing tool, finishing tool, and the like) that process a periphery of the lens are attached and a shaft-to-shaft distance change mechanism which changes a shaft-to-shaft distance between the lens chuck shaft and the processing tool rotational shaft to move the lens relative to a processing tool side direction. The eyeglass lens processing apparatus controls rotations of the lens chuck shaft and controls the shaft-to-shaft distance change mechanism to process the periphery of the lens based on an input target lens shape.
As the shaft-to-shaft distance change mechanism, there are known methods such as a first method (referred to JP-A-2002-205251) which utilizes biasing portion such as a spring to generate a processing pressure onto a carriage that holds the lens chuck shaft when being pressed to a processing tool side, and a second method (referred to JP-A-2004-255561) which directly generates the processing pressure by driving a motor that moves the carriage to the processing tool side without using the biasing portion.
In a mechanism by the first method, the carriage holding the lens chuck shaft is movable along a guide shaft of the shaft-to-shaft distance change mechanism in a processing tool direction. However, a position in the processing tool direction is limited by a guide block that is moved by the motor. Then, the carriage can freely move against a biasing force of the biasing portion in a direction of being away from the guide block. For this reason, in the mechanism by the first method, there is provided a processing end detector which detects whether or not the carriage has reached a position of the guide block.
In a mechanism by the second method, linear movement conversion mechanisms such as a feed screw and a feed nut are moved in a shaft-to-shaft distance direction by the motor to cause the carriage to directly move in the shaft-to-shaft distance direction, and thus, it is possible to control the shaft-to-shaft distance without using the processing end detector. In addition, in the mechanism by the second method, a servo-motor including a rotation detector as the motor that changes the shaft-to-shaft distance is used, and thus, it is possible to verify the processing pressure during processing.